Liquid crystal display device

• US 9,316,881 B2
• Filed: 12/24/2013
• Issued: 04/19/2016
• Est. Priority Date: 12/05/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kimura, Hajime, Uochi, Hideki
• Primary Examiner(s): Wong, Tina
• Application Number:
  US14/140,005
• Publication Number:
  US 20140111727A1
• Time in Patent Office: 847 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 1/134372 for fringe field switching [FFS] where the common electrode is not patterned
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/136209 Light shielding layers, e.g. black matrix, incorporated in the active matrix substrate, e.g. structurally associated with the switching element
• CPC Class Codes: G02F 1/136222 Colour filters incorporated in the active matrix substrate
• CPC Class Codes: G02F 1/136227 Through-hole connection of the pixel electrode to the active element through an insulation layer
• CPC Class Codes: G02F 1/136286 Wiring, e.g. gate line, drain line
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G02F 2201/121 common or background
• CPC Class Codes: G02F 2201/123 pixel
• CPC Class Codes: G02F 2201/124 interdigital

Abstract

It is an object of the present invention to apply a sufficient electrical field to a liquid crystal material in a horizontal electrical field liquid crystal display device typified by an FFS type. In a horizontal electrical field liquid crystal display, an electrical field is applied to a liquid crystal material right above a common electrode and a pixel electrode using plural pairs of electrodes rather than one pair of electrodes.

Claims

1. A liquid crystal display device comprising:

a gate electrode;

a first insulating layer over the gate electrode;

a semiconductor layer over and in contact with the first insulating layer, wherein the semiconductor layer overlaps with the gate electrode;

a source electrode over the semiconductor layer, the source electrode electrically connected to the semiconductor layer;

a drain electrode over the semiconductor layer, the drain electrode electrically connected to the semiconductor layer;

a first transparent conductive layer over and in contact with the first insulating layer, the first transparent conductive layer electrically connected to one of the source electrode and the drain electrode;

a second insulating layer over the first insulating layer, the semiconductor layer, the source electrode and the drain electrode;

a second transparent conductive layer over the second insulating layer, the second transparent conductive layer having a slit; and

a liquid crystal layer over the second transparent conductive layer.

2. The liquid crystal display device according to claim 1, wherein the second insulating layer is in contact with a top surface of the first insulating layer.

3. The liquid crystal display device according to claim 1, wherein the semiconductor layer comprises an amorphous silicon.

4. The liquid crystal display device according to claim 1, wherein the slit has a comb-shape.

5. The liquid crystal display device according to claim 1,

wherein the first transparent conductive layer is a pixel electrode, and

wherein the second transparent conductive layer is a common electrode.

6. The liquid crystal display device according to claim 1, wherein a thickness of the second insulating layer is larger than a thickness of the first transparent conductive layer, wherein the second insulating layer has a stacked-layer structure.

7. A mobile computer comprising:

a display portion comprising the liquid crystal display device according to claim 1.

8. A liquid crystal display device comprising:

a first insulating layer;

a semiconductor layer over and in contact with the first insulating layer;

a first transparent conductive layer over and in contact with the first insulating layer;

a second insulating layer over the first transparent conductive layer;

a first conductive layer comprising a first metal over the second insulating layer, the first conductive layer electrically connected to the semiconductor layer;

a second conductive layer comprising a second metal over the second insulating layer, the second conductive layer electrically connected to the first transparent conductive layer, wherein the second metal is the same as the first metal;

a third insulating layer over the second insulating layer; and

a second transparent conductive layer over the third insulating layer, the second transparent conductive layer having a slit,

wherein the first transparent conductive layer and the second transparent conductive layer overlap with each other with the second insulating layer and the third insulating layer located between the first transparent conductive layer and the second transparent conductive layer.

9. The liquid crystal display device according to claim 8,

wherein the first transparent conductive layer is a common electrode, and

wherein the second transparent conductive layer is a pixel electrode.

10. The liquid crystal display device according to claim 8, further comprising:

a third transparent conductive layer having a slit over and in contact with a surface,

wherein the second transparent conductive layer is over and in contact with the surface.

11. The liquid crystal display device according to claim 8, wherein a part of the first transparent conductive layer and the second transparent conductive layer overlap with each other.

12. The liquid crystal display device according to claim 8, wherein the slit has a comb-shape.

13. A mobile computer comprising:

a display portion comprising the liquid crystal display device according to claim 8.